Why Are Old Assault Claims Against Bill Cosby Back?

As Bill Cosby continues to make headlines around the world — and not for his jokes — the 77-year-old comedian has cancelled two talk show appearances and declined to address decades-old sexual assault allegations that have recently re-surfaced.

Cosby has been accused of sexual assault by more than a dozen women. The allegations surfaced in 2005 when Andrea Constand, the former director of operations of Temple University's women's basketball program, sued Cosby claiming that he had given her pills he called "herbal medication" to help her cope with stress when she visited his Philadelphia-area mansion in 2004 and, after she consumed them, he touched her breasts and genitals and assaulted her.

Constand, who met Cosby in 2002 and thought of him as a mentor, contacted police about the alleged assault but the Montgomery District Attorney declined to pursue charges. On Monday, former Montgomery District Attorney Bruce Castor told NBC Nightly News that he wishes he could have moved forward with the case but felt that he couldn't.

"I didn't say that he didn't commit the crime," Castor said. "There was insufficient admissible and reliable evidence on which to base a conviction beyond a reasonable doubt. That's prosecutor speak for, 'I think he did it but there's just no enough here to prosecute.'"

Constand sued Cosby one month later on allegations of sexual assault and defamation.

As news of that lawsuit spread, 13 other women came forward with similar allegations of drugging and abuse and who were willing to serve as witnesses in Constand's case. Cosby denied assaulting Constand and the lawsuit was settled out of court for an undisclosed amount.

Although many of the women were listed as Jane Doe's, some made their accusations and identities public. California attorney Tamara Green also came forward in 2005 and said on the Today Show that Cosby had drugged and assaulted her. Cosby denied even knowing Green.

In 2006, Philadelphia magazine twice interviewed Barbara Bowman, another witness in Constand's lawsuit. In the stories, Bowman detailed several sexual assaults allegedly at the hands of Cosby.

Why are the allegations on the forefront again?

Last month, stand-up comedian Hannibal Buress lambasted Cosby's alleged behavior and called him a "rapist" during a show in Philadelphia. A clip of his set went viral and people all over the Web began talking about the allegations against Cosby again.

Inspired by the attention, on Nov. 13 Bowman wrote an op-ed for the Washington Post titled: "Bill Cosby raped me. Why did it take 30 years for people to believe my story?"

Then, just this weekend, a new accuser stepped forward. Joan Tarshis alleges that Cosby drugged and assaulted her on two occasions in 1969.

And then Cosby seemed to make it all worse. Last week, a "meme" campaign promoted by the comedian himself ended in disaster. Cosby asked Twitter users to post clever captions under his picture. Many of them referenced the rape allegations.

In the past, he has denied them. On NPR's "Weekend Edition" on Saturday, Cosby refused to answer questions posed by host Scott Simon, simply shaking his head "no." The next morning, Cosby’s lawyer, John P. Schmitt, posted the following statement to Cosby's Web site:

"Over the last several weeks, decade-old, discredited allegations against Mr. Cosby have resurfaced. The fact that they are being repeated does not make them true. Mr. Cosby does not intend to dignify these allegations with any comment. He would like to thank all his fans for the outpouring of support and assure them that, at age 77, he is doing his best work. There will be no further statement from Mr. Cosby or any of his representatives."

On Monday, attorney Dolores Troiani, who represents Andrea Constand, and Schmitt released a joint statement:

"The statement released by Mr. Cosby’s attorney over the weekend was not intended to refer in any way to Andrea Constand. As previously reported, differences between Mr. Cosby and Ms. Constand were resolved to the mutual satisfaction of Mr. Cosby and Ms. Constand years ago. Neither Mr. Cosby nor Ms. Constand intends to comment further on the matter."

Cosby has cancelled appearances on two talk shows to promote his Thanksgiving Day Netflix comedy special. Is that still on track?

Slated to premiere in either summer or fall of next year, the untitled multi-camera comedy is "still in development," an NBC spokesperson told NBC News on Monday. Created by Mike Sikowitz and Mike O'Malley, the show centers on a multi-generational family where Cosby plays the patriarch.